AP Chemistrychapter 16. Acid-Base Equilibria
AP ChemistryChapter 16. Acid-Base Equilibria
Chapter 16. Acid-Base Equilibria
Sample Exercise 16.1 (p. 675)
a) What is the conjugate base of each of the following acids:
HClO4
H2S
PH4+
HCO3-?
b) What is the conjugate acid of each of the following bases?
CN-
SO42-
H2O
HCO3-
Practice Exercise 1 (16.1)
Consider the following equilibrium reaction:
HSO4-(aq) + OH-(aq) SO42-(aq) + H2O(l)
Which substances are acting as acids in the reaction?
a) HSO4- and OH-
b) HSO4- and H2O
c) OH- and SO42-
d) SO42- and H2O
Practice Exercise 2 (16.1)
Write the formula for the conjugate acid of each of the following:
HSO3-
F-
PO43-
CO
Sample Exercise 16.2 (p. 676)
The hydrogen sulfite ion (HSO3-) is amphoteric.
a) Write an equation for the reaction of HSO3- with water, in which the ion acts as an acid.
b) Write an equation for the reaction of HSO3- with water, in which the ion acts as a base.
In both cases identify the conjugate acid-base pairs.
Practice Exercise 1 (16.2)
The dihydrogen phosphate ion, H2PO4-, is amphiprotic. In which of the following reactions is this ion serving as a base?
(i) H3O+(aq) + H2PO4- H3PO4(aq) + H2O(l)
(ii) H3O+(aq) + HPO42- H2PO4- + H2O(l)
(iii) H3PO4(aq) + HPO42- 2 H2PO4- + H2O(l)
a) (i) only
b) (i) and (ii)
c) (i) and (iii)
d) (ii) and (iii)
e) (i), (ii) and (iii)
Practice Exercise 2 (16.2)
When lithium oxide (Li2O) is dissolved in water, the solution turns basic from the reaction of the oxide ion
(O2-) with water. Write the reaction that occurs, and identify the conjugate acid-base pairs.
Sample Exercise 16.3 (p. 677)
For the following proton-transfer reaction, use the above figure (Figure 16.4) to predict whether the equilibrium lies to the left (Kc < 1) or to the right (Kc > 1):
HSO4-(aq) + CO32-(aq) SO42-(aq) + HCO3-(aq)
Practice Exercise 1 (16.3)
Based on the information in Figure 16.4, place the following equilibria in order from smallest to largest value of Kc:
(i) CH3COOH(aq) + HS-(aq) CH3COO-(aq) + H2S(aq)
(ii) F-(aq) + NH4+(aq) HF(aq) + NH3(aq)
(iii) H2CO3 (aq) + Cl-(aq) HCO3-(aq) + HCl(aq)
a) (i) < (ii) < (iii)
b) (ii) < (i) < (iii)
c) (iii) < (i) < (ii)
d) (ii) < (iii) < (i)
e) (iii) < (ii) < (i)
Practice Exercise 2 (16.3)
For each of the following reactions, use Figure 16.4 to predict whether the equilibrium lies predominantly to the left or to the right:
a) HPO42-(aq) + H2O(l) H2PO4-(aq) + OH-(aq)
b) NH4+(aq) + OH-(aq) NH3(aq) + H2O(l)
Sample Exercise 16.4 (p. 679)
Calculate the values of [H+] and [OH-] in a neutral solution at 25oC.
Practice Exercise 1 (16.4)
In a certain acidic solution at 25oC, [H+] is 100 times greater than [OH-]. What is the value for [OH-] for the solution?
a) 1.0 x 10-8 M
b) 1.0 x 10-7 M
c) 1.0 x 10-6 M
d) 1.0 x 10-2 M
e) 1.0 x 10-9 M
Practice Exercise 2 (16.4)
Indicate whether solutions with each of the following ion concentrations is neutral, acidic, or basic:
a) [H+] = 4 x 10-9 M
b) [OH-] = 1 x 10-7 M
c) [OH-] = 7 x 10-13 M
Sample Exercise 16.5 (p. 680)
Calculate the concentration of H+(aq) in
a) a solution in which [OH-] is 0.010 M (1.0 x 10-12 M)
b) a solution in which [OH-] is 1.8 x 10-9 M (5.0 x 10-6 M)
Assume T = 25oC.
Practice Exercise 1 (16.5)
A solution has [OH-] = 4.0 x 10-8 M. What is the value of [H+] for the solution?
a) 2.5 x 10-8 M
b) 4.0 x 10-8 M
c) 2.5 x 10-7 M
d) 2.5 x 10-6 M
e) 4.0 x 10-6 M
Practice Exercise 2 (16.5)
Calculate the concentration of OH-(aq) in a solution in which
a) [H+] = 2 x 10-6 M
b) [H+] = [OH-]
c) [H+] = 100 x [OH-]
Sample Exercise 16.6 (p. 681)
Calculate the pH values for the two solutions described in Sample Exercise 16.5.
(a) 12.00b) 5.25)
Practice Exercise 1 (16.6)
A solution at 25oC has [OH-] = 6.7 x 10-3 M. What is the pH of the solution?
a) 0.83
b) 2.2
c) 2.17
d) 11.83
e) 12
Practice Exercise 2 (16.6)
a) In a sample of lemon juice [H+] is 3.8 x 10-4 M. What is the pH?
(3.42)
b) A commonly available window-cleaning solution has a [OH-] of 1.9 x 10-6 M. What is the pH?
(8.28)
Sample Exercise 16.7 (p. 683)
A sample of freshly pressed apple juice has a pOH of 10.24. Calculate [H+].
(1.7 x 10-4 M)
Practice Exercise 1 (16.7)
A solution at 25oC has pOH = 10.53. Which of the following statements is or are true?
(i) The solution is acidic.
(ii) The pH of the solution is 14.00 – 10.53.
(iii) For this solution, [OH-] = 10-10.53 M.
a) Only one of the statements is true.
b) Statements (i) and (ii) are true.
c) Statements (i) and (iii) are true.
d) Statements (ii) and (iii) are true.
e) All three statements are true.
Practice Exercise 2 (16.7)
A solution formed by dissolving an antacid tablet has a pOH of 4.82. Calculate [H+].
(6.6 x 10-10 M)
Sample Exercise 16.8 (p. 685)
What is the pH of a 0.040 M solution of HClO4? (1.40)
Practice Exercise 1 (16.8)
Order the following three solutions from smallest to largest pH.
(i) 0.20 M HClO3
(ii) 0.0030 M HNO3
(iii) 1.50 M HCl
a) (i) < (ii) < (iii)
b) (ii) < (i) < (iii)
c) (iii) < (i) < (ii)
d) (ii) < (iii) < (i)
e) (iii) < (ii) < (i)
Practice Exercise 2 (16.8)
An aqueous solution of HNO3 has a pH of 2.34. What is the concentration of the acid? (0.0046 M)
Sample Exercise 16.9 (p. 685)
What is the pH of
a) a 0.028 M solution of NaOH? (12.45)
b) a 0.0011 M solution of Ca(OH)2? (11.34)
Practice Exercise 1 (16.9)
Order the following three solutions from smallest to largest pH:
(i) 0.030 M Ba(OH)2
(ii) 0.040 M KOH
(iii) Pure water
a) (i) < (ii) < (iii)
b) (ii) < (i) < (iii)
c) (iii) < (i) < (ii)
d) (ii) < (iii) < (i)
e) (iii) < (ii) < (i)
Practice Exercise 2 (16.9)
What is the concentration of a solution of
a) KOH for which the pH is 11.89? (7.8 x 10-3 M)
b) Ca(OH)2 for which the pH is 11.68? (2.4 x 10-3 M)
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